#include<stdio.h>
	int n,a,k;
int Sum(int n){
	if(n>=2&&k<=100)
	return k+Sum(n-1);
	else
	return 0;
}

int main(){
	scanf("%d%d%d",&n,&a,&k);
	if(Sum(n)==0)
	printf("Wrong Number");
	else
	printf("%d",a+Sum(n));
}
